The great crested newt is the UK's largest newt, reaching a maximum adult overall length of up to about 170mm, although size varies between populations. Mature female length ranges from 90 - 170mm, typically reaching 110-130mm.
Male newts may mature at a length of only 85mm (normally more), and grow to an adult maximum of about 150mm, though more typically 110-120mm. Adults are easily distinguished from the two other native newt species, the smooth and palmate newts, by size and colouring; these two smaller species reach a maximum of around 100mm.
The skin of adult crested newts is granular in appearance. It has a black or dark brown background colour with darker spots, that in males extend onto
the crest. It has very fine white spots on the lower flanks. The male has a jagged crest along the back that dips at the rear of the abdomen, and a smoother edged crest above and below the tail.
The crest decreases in size outside the breeding season. There is a white, silver or grey stripe running from the tail tip along the central, fleshy section of the tail that fades as it approaches the abdomen. Females lack a crest and white tail stripe, but have a yellow-orange stripe running along the bottom edge of the tail. Both sexes have a vivid orange or yellow belly with an irregular pattern of dark black spots or blotches. On land, the great crested newt appears virtually black, and in males the crest shrinks back against the body.
Males of all newts have a relatively more swollen cloaca (vent). The adult male smooth newt has a crest that is wavy rather than jagged, and it does not dip at the start of the top of the tail. It lacks obvious granules in the skin, and is generally lighter in overall coloration, often with roundish black spots.
The belly may be superficially similar in appearance to that of the great crested newt, but the dark markings tend to be more rounded and usually fewer in number in adults. Male palmate newts have a protruding filament at the tail tip, with a low ridge along the back rather than a crest.
Female smooth and palmate newt are very similar in colour and pattern, usually with a beige or brown background colour, with lighter undersides.
Great crested newt eggs have a jelly capsule around 4.5 - 6mm long, with a light yellowish centre, while smooth and palmate newts lay greyish-brown or dirty white coloured eggs, surrounded by a transparent jelly capsule that is about 3mm across. The larvae of great crested newts can be distinguished from the other species by the presence of a filament at the tail tip and black blotches over the body, tail and crest.
They can be very hard to tell apart when they are under 20mm in length. The smooth and palmate newt larvae (which cannot be distinguished by eye) are light beige or brown, sometimes with fine black speckling. Great crested newt larvae are considerably larger, reaching a length of 50 - 90mm before metamorphosis (compared to 30 - 40mm for the smaller species).
On leaving the water, great crested newt juveniles are similar in appearance to adults, apart from lacking the black spots/patterns that develop on the orange belly as they grow.
The pattern becomes 'fixed' as the adults approach maximum size. Males start to develop the secondary sexual characteristics in their second or third season. This is marked by the appearance of the whitish tail stripe and the crest, and normally occurs when newts reach 90 - 120mm in total length. It is impossible to sex great crested newt juveniles externally, as the crest and tail stripe are absent.
Exotic (introduced) European newt species can be encountered occasionally as the result of past release by universities, biological supply companies and hobbyists. Continental forms of crested newt are very difficult to tell apart from native British great crested newt without expert help and analysis. Crested newt species are known to hybridise and the spread of nonnative species and their hybrids is a cause for concern.
Other species such as alpine newt and marbled newt may also have life stages that are, to some extent, similar to those of great crested newts and have been mistaken for them in the past. If you are suspicious about the identity of newts, get them checked by an expert. The release of exotic newts in the wild is undesirable and unlawful and they have an effect on native species.
Prompt removal of exotics can help prevent their spread.
The breeding migration
As the newt breeding season immediately follows winter dormancy, adult great crested newts mature the eggs and sperm they will need for the next year in the previous summer and autumn. Adult newts may feed from the start of the breeding season in order to replenish reserves. Newts that have bred for at least one season may emerge from hibernation with their eggs and sperm ready for the new spring breeding season.
Adult great crested newts normally begin moving from their over-wintering land sites between February and April. The timing of this movement is governed by a number of factors, particularly temperature and rainfall. The first of the newt emergence nights are normally wet or damp, with air temperatures above 4 - 5°C, following several days when the temperature has been just below this level. This makes it less likely that newts will be stimulated to emerge too early by a single unseasonably warm winter's day, only to then find themselves above ground or in the water when freezing conditions return. Movement over land occurs almost exclusively at night.
The migration of newt populations to breeding ponds is normally staggered, with some adults not reaching the pond until May. The earliest arrivals tend to be males. Migration dates are often later to the north and east of Britain, as they are for frogs and other amphibians. There is considerable variation between individuals in the amount of time spent in breeding ponds.
Having entered in early spring, adult newts may spend anything from one day to seven months or more in a pond. At one well-monitored site in England, a third of the population occupied the pond for less than ten days. Therefore, shortly after the main movement into ponds, there may be a period of emigration when newts leave to forage or disperse on land. Newts may also repeatedly move in and out of the breeding pond, as well as between ponds, over the spring and summer.
The main period when breeding adults generally leave the pond is between late May and July. This movement occurs gradually, with most newts having left by August. A proportion however may stay on until October and even, in some ponds, over winter amongst pond sediment and debris. Emigration from the pond usually coincides with periods of rainfall, and there is evidence that newts may leave a pond at or around the same point they entered it, indicating that they return to favoured parts of the terrestrial habitat that they somehow recognise.
After leaving the pond, newts generally seek underground crevices or concealed above ground refuges.
Adult activity on land
On land, great crested newts generally engage in searching for food or dispersing and resting. In summer and autumn when conditions can be very dry for many weeks or in winter when conditions are too cold, they are not seen above ground. Foraging above ground occurs mostly at night, and newts feed over a range of habitat types that support invertebrate prey.
Great Crested Newt habitats in the UK
Great crested newts live in a wide range of mainly lowland habitats, and are by no means restricted to 'natural' environments. They are found primarily in artificially created ponds and terrestrial habitats, or at least those that have been greatly modified by human activities. The farmed landscape provides the most extensive broad habitat type. They appear able to colonise modified habitats relatively quickly if the conditions are favourable and there is a colonising source in the vicinity.
Natural and semi-natural aquatic habitats in which great crested newts occur include marshes, reed beds, spring fed ponds, pingos, bog pools, sand dune pools and ox-bow lakes. As these habitats have become reduced through human activities, overall they contribute less today to great crested newt survival than newer, man-made habitats. However, as these settings represent the "natural state" of the species they are of conservation significance.
Some semi-natural locations support very large and regionally significant populations. In some areas of high pond density, such as north-west England and north Wales, populations are distributed across a dense network of farm ponds within extensive metapopulations.
Populations in this situation are considerably more robust than those where landscapes are fragmented by urbanisation or industry, or where populations are centred on small numbers of isolated breeding ponds. Here, metapopulation structure is poorly developed, with great crested newt colonies being more vulnerable to long-term declines and local extinctions.
Great crested newts occupy a slightly narrower range of habitat types than do the smaller native newts. Both palmate newts and smooth newts may breed in very small ponds (e.g. garden ponds) through to large lakes, while great crested newts tend to be found in ponds in the middle of this range. In addition, great crested newts seem to be more susceptible to the effects of silting and shading. This means that in most landscape types, they may be found in fewer ponds than their smaller relatives.
The lowland farmed landscape
Pastoral (stock grazing) farming is practiced on just under half of agricultural land in lowland Britain, and is a major land use in Wales and south-west, west and north England. The key features of pastoral farmland for great crested newts are that inter-pond distances are low, that grazing pasture can provide good quality foraging habitat which also permits dispersal, and that associated hedgerows, dry stone walls and copses provide additional habitats.
Sheep, horse and cattle grazed pasture are all used by great crested newts. Very short pasture is easily traversed by newts, and provides night time foraging, but little in the way of shelter. Ponds used to be dug out in large numbers on pasture to water stock and sometimes, where soil conditions were suitable, to provide marl, a form of lime rich fertilizer and soil.
Marl pits are typical farm ponds in Cheshire, England Pond with a fence to form a drinking bay for livestock, Flintshire, Walesconditioner. These ponds were often dug in clusters of ten or more. Most were dug during the period from the mid 1700s to the mid 1800s.
Average pond density at that time was 15-20 ponds per km2 but could even reach around 40 ponds per km2 in certain pond-rich areas. The average present day figure is usually very much lower.
Pond losses have been due to natural succession, agricultural intensification, and influences of increased housing, industry, commerce, recreation and road building.
One of the main causes of pond loss has been their general neglect. Without management, many farm ponds have become over-shaded or silted up and have dried out permanently; around half of ponds in many areas are known to be in the late stages of succession.
Although some small samples of the countryside suggest a local slowing of pond loss, relatively few new wildlife ponds have been created. New ponds are mainly dug for fishing or other amenity purposes, which limit their value for great crested newts.
However, the total stock of ponds in some areas such as Cheshire, Lancashire and north-east Wales and parts of East Anglia still result in valuable pond-rich landscapes. In such places great crested newt occupancy reaches 30% and rarely even 50% of ponds on a localised basis, although 5% occupancy is perhaps more typical.
Arable (crop) farming is concentrated in eastern and southcentral England and lowland Scotland, and is the predominant agricultural land use in just over half of farmed lowland Britain. Crop growing imposes a variety of restrictions on the landscape for great crested newts.
For example, the use of pesticides can reduce terrestrial prey density, and fertilisers may run off into ponds causing eutrophication. In addition, ploughing, rolling, harrowing and similar farming practices may inhibit dispersal.
However, the planting of hedges and retention or planting of woodland can provide dispersal, foraging and hibernation opportunities. Ditches may also provide extra breeding sites and dispersal routes. Ponds in arable areas have tended to be lost at a similar, if not slightly higher rate than that in pastoral areas.
Semi-natural grassland and woodland
Unimproved semi-natural grassland and woodland both provide excellent terrestrial habitat for great crested newts, and where there are ponds within colonisation range, good populations can result. Great crested newts may be found in acid, neutral or calcareous grassland.
Deciduous, coniferous or mixed woodland may support newts, though extensive tracts of closed conifer plantation with little understorey and low pH ponds generally provide poor habitat. Great crested newts prefer deciduous woodland with vegetated ground cover and a considerable amount of dead wood on the ground. Areas recently subject to large-scale clear-felling may be of less value.
This is perhaps due to greater exposure caused by temporary loss of ground cover, and ground compaction due to machinery, especially if natural regeneration is suppressed. The value of grassland and woodland is maximised when they occur together as a mosaic, in association with a number of ponds.
Small pond in intensive arable farmland, once used to provide a water supply for livestock
Surveying and Monitoring
Blanket survey :-Blanket surveys cover all ponds within a given area, for example a parish, district or grid square of an Ordnance Survey map. The size of the area will depend on the resources available and pond density. Undertaking these detailed surveys can provide complete information on newt distribution and density of breeding sites along with other information relating to their conservation.
Such information can be useful even beyond the area surveyed. For example if a blanket survey in one area reveals that about one third of local ponds can be expected to support great crested newts, then this can influence planning and land management decisions in areas of similar habitat, even if their ponds have not actually been surveyed.
What data should be collected?
Presence/likely absence For most conservation surveys, the key information to gather is whether newts are present or absent. Theoretically, it is impossible to prove that newts are absent from a site; not finding newts does not mean that they are not there. But in practice it is useful to be able to record animals as absent, or strictly speaking, likely to be absent. Several visits and a variety of survey techniques will be required before it can be concluded that newts are likely to be absent from a site.
Although presence/likely absence surveys are the basis of much great crested newt conservation work, there are situations when it is helpful or necessary to obtain some measure of population size. However, establishing the true size of a newt population is very time-consuming, and is an activity more appropriate to research projects than to conservation work.
Relative abundance is an index or measure of newt numbers seen or captured at a site each year using repeatable methods, and is a more practical option for conservation surveys. It provides a measure of numbers so that, even though actual population size is not known, trends and comparisons can be made between ponds or over time. Relative abundance can be used to:
- assess sites for conservation designation
- compare sites when developing and prioritising conservation strategies
- consider population changes over time
The use of counts of newt numbers to assess populations has evolved from guidelines for the selection of biological SSSIs published by the Nature Conservancy Council in 1989. Guidance relevant to great crested newts and other herpetofauna is also summarised in the Herpetofauna Workers' Manual. Newt populations are scored as low, good or exceptional.
To be eligible for SSSI designation, a great crested newt population normally has to be scored as exceptional over at least three years.
The surveyor should be aware of the limitations of counts. They can vary dramatically for a single population from one day to the next, and in particular, are affected by temperature fluctuations. Also, the variable nature of ponds affects the ease with which newts can be counted.
For example, they may be less easily observed in turbid or weedy ponds. Repeating the counting process can go some way towards compensating for variation in newt visibility in ponds where water clarity varies.
At least three, and preferably six, counts per year are recommended. These should be carried out over the course of the main breeding season, under suitable weather conditions.
The highest count obtained should be used to score the population. If comparisons between population are being made, or if changes in population size over time are being considered, then ideally the average of the same number of counts for each year is used. When assessing populations in a closely-spaced group of ponds (within 250 m of each other) counts can be added together to give a cumulative site score.
If monitoring (measuring population size changes over time) is being undertaken, it should be noted that newt population size can fluctuate between years, sometimes quite considerably.
This is not necessarily a cause for concern, but may be part of a normal process. Long-term monitoring, ideally over many years, is needed to reveal any meaningful trends in newt populations.
As described in previously, the great crested newt is strictly protected in Britain through the Wildlife and Countryside Act 1981 (as amended) and the Conservation (Natural Habitats etc.) Regulations 1994. This legislation not only protects great crested newt habitat, but also makes it an offence to capture or disturb the species.
A licence allows an otherwise unlawful activity to occur for a certain reason, such as conservation. If it is anticipated that great crested newts will be encountered during a survey, then generally it is advisable to obtain a licence first, and certainly if you are going to use methods which involve capture or disturbance (licences are issued by the relevant Statutory Nature Conservation Organisation).
Surveying and Monitoring
Site owners and managers may wish to assess the status of a resident newt population over time, by keeping a record of survey data. It is recommended that night torch surveys or bottle-trapping be used for this purpose. Regular counts, of at least three, and preferably six per season, may help develop a picture of the state of the great crested newt population. The graphs show examples of monitoring over a period of years. The peak counts (if the number of counts remains constant year to year) or the mean counts may be used to monitor the effects of management techniques or other changes.
Landscape Planning LTD is a multi-disciplinary consultancy practice that supplies Arbirocultural, Ecology and Landscape services Our ecologists are fully licensed to survey for Great Crested Newts and are experienced in planning suitable mitigation proposals.
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